There is known a heat pump system using waste heat that has a compression heat pump circuit using the shaft output of a power engine as a power source for a compressor which compresses refrigerant, and an absorption heat pump circuit using waste heat of the power engine as a heat source for a regenerator which heats absorbing liquid (see Patent Document 1, for example). In this heat pump system using waste heat, refrigerant passing through a use-side heat exchanger of the compression heat pump circuit is circulated to an absorber of the absorption heat pump circuit, separated after regenerated by the regenerator, and supplied to the discharge side of the compressor of the compression heat pump circuit.